The present invention relates to molds for tires. More particularly, the invention relates to a mold for shaping the beads of tires.
In tubeless, pneumatic tires the beads provide two functions: to anchor the tire to the wheel and to form a seal with the rim to close the air cavity. Conventional pneumatic tires rely on the exterior (relative to the tire cavity) portion of the tire bead to seat on the wheel rim for these functions. In certain types of tires, for example, vertically anchored tires such as the PAX brand tire available from Michelin North America, Inc., the interior portion of tire bead contacts the wheel rim to form the air seal.
To mold the interior portion of the tire bead, it is necessary to introduce a mold element in the interior of the tire. The tire molding art contains examples of bead molding parts that allow the uncured tire to be introduced into the mold without deforming the bead, and then expand to clamp on the bead for molding. For example, U.S. Pat. No. 6,238,193 to Bosseaux, which is commonly owned with the present invention, discloses a bead molding ring that includes radially moving parts and pivoting parts that mate in an expanded, molding position, and retract to allow the tire to be loaded and removed from the mold.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention.
In one exemplary embodiment, the present invention provides a mold for a tire that includes a loading plate defining a cavity and having a central axis. A base is received within the cavity. The base has an engagement surface and is movable along the central axis. An actuator is also movable along the central axis between a spaced position and an engaged position relative to the base. The mold includes at least one sliding section movably attached to the engagement surface. The sliding section is movable in a direction perpendicular to the central axis between an engaged position and a retracted position, and has a molding surface for a tire bead. The mold also includes at least one floating section movably attached to the engagement surface and movable on a diagonal axis relative to the central axis between an engaged position and a retracted position. The floating section has a molding surface for a tire bead. Movement of the actuator from the spaced position to the engaged position moves the at least one sliding section and the at least one floating section to the respective engaged positions so that the respective molding surfaces join to form a continuous molding surface for the tire bead.
For the exemplary embodiment being discussed, the actuator may have a frustoconically shaped driving surface for mating contact with at least one sliding section and at least one floating section. Such sections in turn have frustoconically shaped follower surfaces for being driven by the actuator. Additionally, each of the floating sections and sliding sections may be configured with joining surfaces, which mutually bear on one another when the respective sections are in the engaged position. Such exemplary features allow the application of a uniform pressure by a continuous, sealed surface against the tire bead. Accordingly, the tire bead may be molded into the desired shape and left with a smooth surface for forming an air tight seal.
In addition, this exemplary embodiment may be configured such that at least one floating section is biased to the retracted position spaced along the central axis from said base and radially inward toward the central axis. Furthermore, at least one sliding section may be configured such that it is biased to the retracted position radially inward toward the central axis.
In another exemplary embodiment of the present invention, a mold element for shaping a tire bead is provided and includes a platform having a support surface. A base resides over the platform and has a first surface and a second surface. The base is supported by a plurality of springs in mechanical communication with the first surface and the support surface. A plurality of floating sectors are connected to the second surface and are configured for simultaneous radial and axial movement. Each of floating sectors has a tire bead molding surface located along the outer radius and has a drive surface located along the inner radius. A plurality of radial sectors are connected to the second surface and are configured for radial movement. The radial sectors each have a tire bead molding surface positioned along the outer radius and each have a drive surface located along the inner radius. An actuator having a contacting surface is positioned over the base. Upon causing the actuator to move towards the platform, the contacting surface of the actuator contacts the drive surfaces to move the plurality of floating sectors and the plurality of radial sectors so as to cause the tire bead surfaces to form a uniform, sealed surface for application to the tire bead.
In another exemplary embodiment of the present invention, a mold element for a tire is provided that includes an annular disk comprised of a plurality of movable sectors. The annular disk has an axis about which the sectors are radially located. Each movable sector has a molding surface located along its outer radius that is configured for contact with a bead of the tire. At least one of the plurality of movable sectors is configured for radial movement between a release position and an engaged position. At least one of the plurality of movable sectors is configured for simultaneous radial and axial movement between a release position and an engaged position. An actuator is positioned above the annular disk and is configured for selectively acting upon the annular disk so as to move the plurality of movable sectors between the release position and the engaged position. Upon being placed into the engaged position, the mold surfaces of the plurality of movable sectors collectively form a continuous surface for molding the tire bead.
Another exemplary embodiment of the present invention provides a tire mold that includes a circular member having a series of alternately positioned radial sectors and diagonal sectors. The radial sectors are configured for movement in a radial direction between a release position, in which the tire may be placed upon or removed from the mold, and a secure position, in which a bead of the tire is in contact with the series of alternating radial sectors and diagonal sectors. The diagonal sectors are configured for movement simultaneously in both an axial direction and a radial direction between the release position and the secure position. An actuating member is positioned axially above the circular member and is configured for contacting the radial and diagonal sectors so as to selectively, reciprocally position the radial and diagonal sectors between the release position and the secure position. Upon being placed into the secure position, the series of radial and diagonal sectors collectively create a uniform surface for contacting and molding the bead of the tire.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the principles of the invention. As will be understood by one of ordinary skill in the art using the teachings disclosed herein, the present invention as set forth in the claims herein exists in a variety of different embodiments that may be used to secure the position of a tire as needed.